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Re: [Discuss-gnuradio] detecting spectrum holes

From: Vladimir Dergachev
Subject: Re: [Discuss-gnuradio] detecting spectrum holes
Date: Thu, 22 Mar 2012 05:23:03 -0700 (PDT)
User-agent: Alpine 2.02 (DEB 1266 2009-07-14)

On Wed, 21 Mar 2012, John Ewan wrote:

I have had enough about this. What the heck is a spectrum hole.
I am pretty sure this is probably a term brought up by some........

There are NO spectrum holes. Learn about black body radiation
and KTB........

A spectrum hole is a part of spectrum nobody can sue you for using.


                  Vladimir Dergachev

Sorry folks. the term has always erked me.

We can talk about white space.....that I can take.

On 3/21/12, Abdelrahman Ahmed <address@hidden> wrote:
2012/3/19 Alexander List <address@hidden>

On 01/-9/-28163 03:59 AM, Abdelrahman Ahmed wrote:

i'm new to this ,i need your help on how to start detecting spectrum in TV
band and holes in this spectrum.


though others will probable be able to give you more in-depth directions
wrt spectrum sensing, just out of curiosity, what's your use case?

Are you looking into TV white spaces? [1]

Most likely you'll want to use the USRP1 with WBX because I assume it has
better sensitivity than TVRX.

Why would you want to transmit anything if you're just looking into
analyzing spectrum usage in TV channels?

LP0410 is covering the right frequency band for UHF (400 MHz to 1 GHz),
but it is a directional antenna. Is that what you want? Otherwise, you
might be better off using an omni antenna, preferably on a roof...

Here are a few pointers to papers on TV white spaces:


I've posted some of the key issues on this list two years ago:


Dyspan has some nice papers on spectrum sensing as well:



Now to the setup:

*Hardware / sample data*

I have a USRP1, two WBX, USRP1 N210 and an PC hardware available as well,
so unless you're in a closed source / NDA environment, we could set up a
code repository on github, and I could provide you with sample recordings
from Hong Kong to cross-check detectors.

*Regulatory environment / signals too look for*

What is your location? From your signature, I assume you're in the Middle
East, and I guess we're talking mostly about DVB-T signals. Is there still
analog TV transmission around, wireless microphones, ...?

*gnuradio packages on Ubuntu*

The gnuradio packages that come with Ubuntu 10.04 are most likely a bit
outdated, so you might want to upgrade your laptops to 11.10 first.

10.04 contains 3.0.4-2ubuntu1 (http://packages.ubuntu.com/hardy/gnuradio)
11.10 contains 3.2.2.dfsg-1ubuntu7 (

Once you've got 11.10 with the latest packages installed, you might want
to test your setup with some of the gnuradio examples, like a basic FM
receiver to tune in a local radio station.

Hope this helps for a start - please let us/me know on the mailing list if
you need more input :)


[1] http://en.wikipedia.org/wiki/White_spaces_(radio)

hi ,
problem 1
i pugged usrp into usb and run usrp_fft.py and i got signal like noise it's
amplitude -60 dB.
i also can run usrp_spectrum_sense.py but only numbers of frequencies
appeared below each other (min freq and max freq).

problem 2
when i plugged out usrp from usb and run usrp_fftw.py again  it told me
that can not open usrp.
and when i try benchmark_tx.py and benchmark_rx.py on the other lap, there
is an error appeared told me that
can not find module usrp_transmit_path

problem 3
- when i write usrp_probe i can not get any info about my usrp1.
- when i write uhd_find_devices it told me that:

Could not locate USRP1 firmware

Please install the images package

so from these problems some programs can identify the usrp1 and the
other not, so what is happening here.

Abdelrahman ahmed


arab academy for science and technology and maritime transport

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